Sound like a bad flyback? (Solved)

[brad808]

Started off a couple days ago where the image would start to shake. Even with no source connected the "please check imput source" or whatever it says error message would shake. Sort of a zooming in and out really fast.

Connected a computer to it and same thing. However when I had a window open in the center of the screen it would "focus" and the image would stabalize. As I dragged the window towards one of the edges of the monitor or minimized it, the zooming effect would return. I did notice that turning the brightness way up to an unusable level would stabalize the image regardless of window open or not.

Both the screen and focus pots appear to be working (however I did hear a couple crackles a few days back). Adjusting the flyback does have some effect on it but like I said in order to be stable it has to be unusably bright.

I've tried relowing a bunch of solder joints on the chassis and neckboard even though they appear to be fine. I tried switching the "focus" cable to the second focus pot on the flyback... same issue.

KT-2938F is the monitor

[grantspain]

had this happen with a kt2914f and it was indeed flyback transformer-looks real wierd when it happens

at first i thought it was unstable b+ but that was rock solid

[MonMotha]

KT-2914F/DF (and, even worse, the KT-3414DF) is indeed well known for this.  You get a "pulsating" effect in both overall brightness and image size (all dimensions) especially when a bright image is being displayed.  Cause is usually indeed the flyback.  I don't know anything about the KT-2938F, unfortunately.

A somewhat similar problem apparently happens with some frequency on some Sony monitors and is also due to a bad flyback, but the root cause is actually a tube fault (which breaks the flyback).

[brad808]

OK I'll probably order the flyback and see if that helps.

Pretty sure I already know the answer to this one but no way to open it up and "repair" it? Saw some pics of split open flybacks and they seem to be pretty simple inside  . $85 for a new one...

[grantspain]

$85 is not expensive,they are about $120 in the u.k

[brad808]

$85 is not expensive,they are about $120 in the u.k

That's true. I went ahead and ordered one. Just wanted to make sure there was no easy $2 fix for the old one.

[brad808]

Just to update this thread I received and installed my new flyback tonight... Works amazing now! 

Thanks for all the help